* feat/upload-bar: add a upload bar when user upload file, indicate the upload process
* feat/save-loading-status: add save status when click back button from editor
* fix: address PR review issues in upload and save features
- Replace deprecated substr() with substring() in UploadContext
- Fix broken error handling that checked stale task status
- Fix missing useEffect dependency in UploadStatus
- Fix CSS class conflict in progress bar styling
- Add error recovery for save state in Editor (reset on failure)
- Use .finally() instead of .then() to ensure refresh on upload failure
- Fix inconsistent indentation in UploadContext
* fix e2e tests
---------
Co-authored-by: Zimeng Xiong <zxzimeng@gmail.com>
adamant368